Switch rail height gauge is mainly used to measure the descent height value of the switch rail relative to the basic rail and point rail relative to the wing rail . This instrument has the features of high measuring precision, convenient calibration, simple structure, light weight and easy to carry. Reasonable switch rail height can not only ensure train running safely and smoothly, but also reduce the interaction between wheel and rail effectively,reduce the dynamic stress of track structure, keep the track in good geometric state, thus reduce the maintenance workload.